1. Field of Invention
The present invention relates to the field of integrated circuit, and more particularly to a clock generation circuit.
2. Description of Related Arts
A clock generation circuit is an important part of the integrated circuit design. Usually, off-chip crystals or crystal oscillators are used in integrated circuits to provide accurate clock sources. But the system cost is increased at the same time. Therefore, it is very necessary to design a precious on-chip clock generation circuit.
In traditional on-chip clock generation circuits, a ring oscillator capable of being compensated by process, voltage, temperature, etc. or a RC oscillator is often adopted for generating an accurate clock cycle. However, the ring oscillator capable of being compensated by process, voltage, temperature is more complex to be designed, and more difficult to be technically implemented technical. On the other hand, although it is simple to design a RC oscillator, influenced by the process variations among resistor and capacitor, the accuracy of the clock frequency is limited.